I'd build one from one of the Stewart shells, they turn up now and again pretty cheap (I saw one at Springfield for like $10). Last I knew Stewart still sold them new, but that was before they sold out to Bowser.
The hood being seperate pieces makes it easier to chop or remove the short nose; an Athearn switcher cab aught to be a cheap way to come up with the EMD cab face for the 9950 although a Cannon cab may be easier to work from. Number boards would have to be dismembered from the nose of an SW1001 or SW1500 shell.
Was this unit wrecked maybe? I know the Dewitt RSD-15/RSD-5 slug set, the radiator end on the RSD was replaced with part of a hood from an RS1 or S-type switcher for that reason.
This is basically the first "DeWitt Geep" even though it wasn't done there, enough were to give the 1200 HP RS2/3 rebuild that nickname. It should have a 1200-hp rated 567-12 from a retired E-unit. I can't remember how many PC built, some got strange extended housings on the hoods (one is visible to the left of this photo:
http://www.rrpicturearchives.net/showPi ... ?id=197929 ) .
The result is basically a large/heavy SW1200 with GE traction motors and room for a toilet (on units retaining a short hood) so they could be used a little more flexibly. The twin EMD type stacks and small EMD fans give the prime mover conversion away on these units.
They were successful enough the EL did one and Conrail continued to build about 30 more, through number 9999, but they became the units that went in and out of storage first and around 1988 when the B40s came they bumped enough newer units down that I'm pretty sure that's when these were retired as a group. I know the last time I saw one was in 1985, but I was a kid then so I didn't get to railfan much. Amtrak either bought, or built, about half a dozen similar units too.
At least one of every Conrail road that had these got done - LV, RDG, CNJ, Erie and DL&W, and PC. I'm not sure how many are left outside of former LV-211 (actually a PC/PRR unit before that) in Rochester, an ex-DL&W on Housatonic, and 2 or three on the Maryland & Delaware (I believe one each DL&W and Erie and not sure on the other one). At least two of the Amtrak units do exist, and those were PC units originally.